title: IL-4-induced selective clearance of oligomeric beta-amyloid peptide(1-42) by rat primary type 2 microglia.
abstract: A hallmark of immunopathology associated with Alzheimer's disease is the presence of activated microglia (MG) surrounding senile plaque deposition of beta-amyloid (Abeta) peptides. Abeta peptides are believed to be potent activators of MG, which leads to Alzheimer's disease pathology, but the role of MG subtypes in Abeta clearance still remains unclear. In this study, we found that IL-4 treatment of rat primary-type 2 MG enhanced uptake and degradation of oligomeric Abeta(1-42) (o-Abeta(1-42)). IL-4 treatment induced significant expression of the scavenger receptor CD36 and the Abeta-degrading enzymes neprilysin (NEP) and insulin-degrading enzyme (IDE) but reduced expression of certain other scavenger receptors. Of cytokines and stimulants tested, the anti-inflammatory cytokines IL-4 and IL-13 effectively enhanced CD36, NEP, and IDE. We demonstrated the CD36 contribution to IL-4-induced Abeta clearance: Chinese hamster ovary cells overexpressing CD36 exhibited marked, dose-dependent degradation of (125)I-labeled o-Abeta(1-42) compared with controls, the degradation being blocked by anti-CD36 Ab. Also, we found IL-4-induced clearance of o-Abeta(1-42) in type 2 MG from CD36-expressing WKY/NCrj rats but not in cells from SHR/NCrj rats with dysfunctional CD36 expression. NEP and IDE also contributed to IL-4-induced degradation of Abeta(1-42), because their inhibitors, thiorphan and insulin, respectively, significantly suppressed this activity. IL-4-stimulated uptake and degradation of o-Abeta(1-42) were selectively enhanced in type 2, but not type 1 MG that express CD40, which suggests that the two MG types may play different neuroimmunomodulating roles in the Abeta-overproducing brain. Thus, selective o-Abeta(1-42) clearance, which is induced by IL-4, may provide an additional focus for developing strategies to prevent and treat Alzheimer's disease.
authors.affiliation: Department of Molecular Cell Function, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Shimizu
authors.forename: Kohichi
authors.initials: K
authors.lastname: Kawahara
authors.forename: Makoto
authors.initials: M
authors.lastname: Kajizono
authors.forename: Makoto
authors.initials: M
authors.lastname: Sawada
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakayama
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D018955:CD36 Antigens / Q000096:biosynthesis / Q000235:genetics; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D019281:Dimerization; D006801:Humans; D007339:Insulysin / Q000096:biosynthesis / Q000235:genetics; D015847:Interleukin-4 / Q000502:physiology*; D051907:Lysosomal Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D017628:Microglia / Q000145:classification / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D015260:Neprilysin / Q000096:biosynthesis / Q000235:genetics; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D051116:Receptors, Scavenger / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation / Q000276:immunology
chemical_list: D016229:Amyloid beta-Peptides; D018955:CD36 Antigens; D051907:Lysosomal Membrane Proteins; D010446:Peptide Fragments; D051116:Receptors, Scavenger; C075222:amyloid beta-protein (1-42); C070693:Scarb2 protein, rat; D015847:Interleukin-4; D015260:Neprilysin; D007339:Insulysin